[Samba] SMB client signing?

[tvsjr]

I'm having a bit of trouble getting a share to mount:

[root at firewall samba]# kinit tvsjr
Password for tvsjr at HOME.TVSJR.COM: <password>
[root at firewall samba]# smbclient -k //server01/e$
smb: \> quit
[root at firewall samba]# mount -t smbfs -o username=tvsjr,krb //server01/e$ /data
Warning: kerberos support will only work for samba servers
cli_negprot: SMB signing is mandatory and we have disabled it.
2054: protocol negotiation failed
SMB connection failed
[root at firewall samba]#

My smb.conf:
[global]
realm = HOME.TVSJR.COM
encrypt passwords = yes
password server = SERVER01
workgroup = HOME
security = ADS
client use spnego = yes
client signing = yes
server signing = yes

I'm trying to mount a share from a Windows 2K, XP, or 2k3 box. Any suggestions?

Thanks,
Terry